Core for proppant and process for its production

Abstract

Disclosed is a proppant core, having low density and high strength and a process for its production. The proppant core is especially useful in crude oil and natural gas extraction. The proppant properties are achieved by virtue of the raw material mixture consisting of melt phase former and at least one further component and containing less than 35% Al2O3. The process includes mixing the raw material components, homogenizing, granulating and then thermally treating the cores.

Description

Working examples of the invention are explained in detail with reference to drawings. In the drawings:

FIG. 1 shows a schematic section view of a core without coating,

FIG. 2 shows a schematic section view of a core with coating,

FIG. 3 shows a schematic view of a rotary tube oven unit for the thermal treatment, and

FIG. 4 shows a schematic view of a fluidized bed unit for the thermal treatment.

Claims

1. A core which is formed from a raw material mixture comprising a melt phase former and at least one further substance which comprises oxygen compounds, wherein the raw material mixture containing less than 35% Al2O3.

2. The core of claim 1 wherein the further substance comprises clay.

3. The core of claim 1 wherein the further substance comprises ashes or dusts from thermal processes.

4. The core of claim 1 wherein the core has a density of less than 2 g/cm3 when in a thermally treated state.

5. The core of claim 1 wherein the core has a particle size of 0.2 mm to 2 mm when in a thermally treated state.

6. The core of claim 1 wherein an organic material is added to the raw material mixture.

7. The core of claim 1 wherein liquid or solid high-energy organic substances are added to the raw material mixture.

8. The core of claim 1 wherein the melt phase former in the raw material mixture being less than 20%.

9. The core of claim 1 wherein the melt phase former is in liquid or solid form and comprises alkali metal carbonates, alkali metal hydroxides, alkali metal hydroxide solutions or combinations thereof.

10. The core of claim 1 further comprising a coating.

11. The core of claim 10, wherein the coating comprises an inorganic or organic material.

12. The core of claim 1 further comprising an impregnation of the core in the.

13. (canceled)

14. A process for producing the core of claim 1 comprising mixing the raw material components and granulating to form cores then subjecting the cores to a thermal treatment in the temperature range from 800° C. to 1100° C.

15. A process for producing the core of claim 1 comprising mixing the raw material components and conditioning to form a suspension, spraying the suspension into a thermal reactor then subjecting the cores to a thermal treatment in the temperature range from 800° C. to 1100° C.

16. The process of claim 14 further comprising adding a liquid medium before, during or after the mixing.

17. The process of claim 14 further comprising adding liquid or solid assistants before, during or after the mixing.

18. The process of claim 14 further comprising treating the cores in a granulating pan before the thermal treatment.

19. The process of claim 14 further comprising adding seeds to form the cores.

20. The process of claim 14 further comprising utilizing a separating agent.

21. The process of claim 20 further comprising powdering the cores with the separating agent before the thermal treatment.

22. The process of claim 20 wherein the separating agent is blown into the sintering zone (5) during the thermal treatment.

23. The process of claim 14 wherein thermal treatment takes place in a countercurrent rotary tube oven which is heated directly or indirectly.

24. The process of claim 14 wherein the thermal treatment takes place in a fluidized bed.

25. The process of claim 14 further comprising coating or impregnating the cores.

26. The process of claim 14 further wherein the thermal treatment is followed by a cooling process.

27. The process of claim 26 wherein after the cooling process the cores are coated or impregnated.

28. The process of claim 26 wherein during the cooling process, the cores are coated or impregnated.